Revista Chilena de Historia Natural 84 (1): 97-106, 2011
RESEARCH ARTICLE
Distribution and abundance of the South American sea lion Otaria
flavescens (Carnivora: Otariidae) along the central coast off Chile
The onshore distribution and abundance of the South American sea lion
Otaria flavescens along the central Chilean coast was estimated during the period January-February 2007.
Additionally, changes in population abundance during the period 1970-2007 were examined. Population surveys were
based on photographs taken from boats or aircraft. A total of 16301 sea lions (CI = 16209-16375) were counted in 33
colonies (6 breeding and 27 non-breeding sites). After correction to account for the proportion of individuals at sea and for
pups not seen at the time of the survey, the mean estimated abundance was 18179 (95 % CI = 17777-18851) sea lions.
Population trend analysis showed that from 1970 to 1985, South American sea lions showed a positive increase of
approximately 2.1 % yr<sup>-1</sup>. Nevertheless, between 1985 and 1997 and between 1997 and 2007, the
estimated number of sea lions showed a stable or slightly negative trend of 0.4 ± 0.1 % yr<sup>-1</sup> and 0.5 ±
0.1 % yr<sup>-1</sup>, respectively. We suggest that the overexploitation and decline of the principal fisheries
in Central Chile could adversely impact the abundance and distribution of the South American sea lion in the study
area.
Key words:
census,
Chilean coast, Otaria flavescens, overexploitation, sea lions
